Spinning, processing, and applications of carbon nanotube filaments, ribbons, and yarns

Abstract

Coagulation spinning produces structures such as fibers, ribbons, and yarns of carbon nanotubes. Stabilization, orientation, and shaping of spun materials are achieved by post-spinning processes. Advantages include the elimination of core-sheath effects due to carbonaceous contaminants, increasing mechanical properties, and eliminating dimensional instabilities in liquid electrolytes that previously prohibited the application of these spun materials in electrochemical devices. These advances enable the application of coagulation-spun carbon nanotube fibers, ribbons, and yarns in actuators, supercapacitors, and in devices for electrical energy harvesting.

Description

[0001] This application claims priority to application Ser. No. 09 / 946,432, filed Sep. 4, 2001, the entire contents of which are hereby incorporated by reference. This application claims priority to provisional Application No. 60 / 245,161, filed Nov. 3, 2000, the entire contents of which are hereby incorporated by reference.[0003] Methods are described for spinning fibers, ribbons, and yarns comprised of carbon nanotubes; the stabilization, orientation, and shaping of spun materials by post-spinning processes; and the application of such materials made by spinning.DESCRIPTION OF RELATED ART[0004] Since the discovery of carbon nanotubes by lijima and coworkers (Nature 354, 56-58, (1991) and Nature 361, 603-605 (1993)) various types of carbon nanotubes (NTs) have been synthesized. A single-wall carbon nanotube (SWNT) consists of a single layer of graphite that has been wound into a seamless tube having a nanoscale diameter. A multi-wall carbon nanotube (MWNT), on the other hand, compri...

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Problems solved by technology

The problem has been that no methods are presently available for the manufacture of nanotube articles that have these needed characteristics.

This obstacle has so far hindered applications development.

The problem is that MWNTs and SWNTs are insoluble in ordinary aqueous solvents and do not form melts even at very high temperatures.

Unfortunately, the fibers made by the CS process are not useful in applications as electrodes immersed in liquid electrolytes because of a surprising shape memory effect.

Because of this structural instability of fibers made by the CS process, they are unusable for critically important applications that use liquid electrolytes, such as in supercapacitors and in electromechanical actuators.

Another drawback of the current CS process is that it has been successfully applied only for nanotube-containing samples that contain an enormous amount of carbonaceous impurities (about 50% by weight or more).

Practice of this CS process with purified nanotubes has been universally unsuccessful, which has suggested that the carbonaceous impurities might be playing an important role in the initial stage of the CS spinning process.

Because of the presence of these impurities, the as-spun carbon nanotubes fibers contain about 50 volume percent of carbonaceous impurities, which degrade mechanical and electronic properties.

In addition, since the CS process does not enable a substantial mechanical draw, the obtained modulus of the fibers made

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